1. Field of the Invention
The present invention relates to a weigh scale using multiple, digital, load cells for providing substantially enhanced accuracy and significantly greater convenience in compensating for load position. More particularly, the present invention relates to a weigh scale in which the excitation of each load cell is digitally controlled, preferably from a central controller.
2. Description of the Prior Art
In a platform scale using multiple load cells, the weight of the object being weighed is determined as the total of the individual load cell outputs which are typically summed electronically. This weight total indication can vary, however, in accordance with the position of the object on the platform. This is due to cell mounting inaccuracies, mounting non-repeatability errors, cell calibration inaccuracies, and cell response to off-axis forces.
In order to compensate for this phenomenon, prior art load cells have been equipped with a potentiometer for varying the excitation voltage of the individual load cells. Procedurely, a weight is repetitively placed on the platform over each load cell and each associated potentiometer adjusted in turn until compensation is achieved. This procedure requires many repetitions and is particularly inconvenient and time consuming because the installer must adjust each potentiometer usually from location within the scale pit.